Britain's diverse and highly competitive newspapers are generally more freewheeling, uninhibited and populist than their U.S. counterparts. They also tend to cross more lines. Last year, one of them was caught hacking into the cellphones of celebrities and other news subjects, including a missing girl who was later found dead. Though the paper, owned by Rupert Murdoch's News Corp., was later shut down, the government launched a wide-ranging investigation, led by a senior judge, into the industry's practices. The perhaps inevitable result is a lengthy report and a series of dangerously overreaching proposals.

Lord Justice Brian Leveson's report recommends, among other things, that Parliament pass a law setting up an independent body to regulate the press that would be empowered to impose fines of up to $1.6 million and mandate the publication of corrections or retractions by newspapers. Though the members of the panel would not be politicians, a state agency that currently regulates radio and television would be charged with assessing its work. If Leveson had his way, newspapers would face restrictions on protection of sources and access to information, and even a limit on circulation.

These ideas are, to begin with, deeply impractical: Leveson all but ignored communication on the Internet, which in Britain, as in the United States, is rapidly eclipsing newspapers as a news source. Under his scheme, the same rules that applied to populist tabloids seeking dirt on celebrities would also govern more serious practitioners, inhibiting the investigative journalism that is vital to a democracy. Foreign Secretary William Hague reportedly warned that the legislation would hurt Britain's reputation for freedom and would be used by autocrats like Russia's Vladimir Putin to justify repression of free speech.

Fortunately, Prime Minister David Cameron opposed the law's enactment, saying that doing so would “cross the Rubicon” toward state regulation of the press. But the prime minister is under pressure from the Social Democratic Party, which is part of his coalition, as well as the opposition Labor Party, which both favor the regulation plan.

British newspapers are meanwhile scrambling to replace a self-monitoring council with a stronger organization like the one Leveson recommends but without statutory backing. That ought to suffice. Journalists who commit crimes — such as hacking into cellphones — should be held accountable by the courts. But any attempt to regulate newspapers by law is injurious to freedom and, in the Internet age, unworkable.